Illumination devices are employed in a wide variety of contexts. Various types of fine work require high intensity illumination over a small area a relatively short distance from the eyes of a user. Examples of such fine work include surgery and dentistry, as well as watch and jewelry repair. A relatively narrow beam is desirable for such applications. In other applications, illumination at a greater distance, or at a larger area, may be needed. Others who work at night or in areas lacking in illumination, such as rescue workers, miners, and utility workers, may require illumination at a greater distance, or over a larger area. Enhanced illumination may also be desirable in normal light conditions for persons having low vision.
One source of illumination is a light emitting diode. A commercial light emitting diode typically is in the form of a package having therein a die covered by a lens. The die typically includes an array of light emitting elements covered by a lens. Light is emitted by a typically commercial light emitting diode over a full semi-spherical range, with greater intensity in the forward direction. One device employed to provide a relatively narrow field of illumination is a collimator. An example of such a collimator is the Fraen Fiber Light Injector, from Fraen Corporation, of Reading, Mass. Such a collimator provides a beam which tends to diverge gradually.